Stents are placed or implanted within a blood vessel for treating stenoses, strictures or aneurysms therein. They are implanted to reinforce collapsing, partially occluded, weakened, or dilated sections of a blood vessel. They have also been implanted in other bodily vessels including arteries, veins, biliary ducts, urethras, fallopian tubes, bronchial tubes, the trachea and the esophagus.
Stents are typically either self-expanding or mechanically expandable via the application of radially outward force from within the stent, as by inflation of a balloon. An example of a balloon expandable stent is shown in U.S. Pat. No. 5,843,120. An example of a self-expanding stent is described in WO 96/26689. Hybrid stents, e.g. stents which are both self-expanding and mechanically expandable are also known. Examples of hybrid stents are disclosed in U.S. Pat. No. 6,168,621 and WO 01/08600.
The use of coatings which contain active pharmacological agents or drugs for therapeutic uses such as inhibiting restenosis is known in the art. While the use of therapeutic coatings holds enormous promise, one limitation that occurs with coatings arises due to the work hardening nature of the stainless steel that is typically found in many stents. After deployment of the stent and after the therapeutic coating has had an effect on the vessel in which the stent is implanted, there is a possibility that the stent may lose its initial tight fit in the vessel which could result in migration of the stent.
There remains a need for a stent which provides some of the benefits of balloon expandable stents and self-expanding stents and which, in particular, when provided with a therapeutic coating, will maintain a tight fit in a vessel even after the coating has had an effect on the vessel.
All U.S. patents and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.
Without limiting the scope of the invention, a brief summary of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below.
A brief abstract of the technical disclosure in the specification is provided as well for the purposes of complying with 37 C.F.R. 1.72.